This invention relates to a gas bag module comprising a gas bag.
There are gas bags in which an outer contour of the gas bag is defined by a gas bag wall which has a front wall for the impact of the occupant with a centric opening as a transition to an indentation in the gas bag, the indentation being formed in that during inflation a center portion of the gas bag wall is prevented from freely moving and is restrained. In such ring-shaped gas bags, the center portion which in a conventional gas bag is presented to the occupant, is prevented from moving towards the occupant in that it remains fixedly attached to the module. In this arrangement, restraint is effected via the ring-shaped front wall around the indentation. The indentation which is not filled with gas is to be as small as possible so as to help the head of the occupant to be intercepted as safe as possible.
The invention provides a gas bag module in which the indentation is closed at least in part, preferably even completely closed. This is achieved in a gas bag module which comprises a gas bag, an outer contour of the gas bag being defined by a gas bag wall which has a front wall for the impact of an occupant with a centric opening as a transition to an indentation in the gas bag. The indentation is formed in that during inflation a center portion of the gas bag wall is prevented from a free movement, preferably from any movement, and is restrained. A closure part is provided which encloses one of the indentation and the opening and engages the gas bag wall. A traction means is connected with the closure part. The traction means is attached such that due to a deployment of the gas bag a tensile force is exerted on the traction means and the tensile force is passed on to the closure part, and one of the indentation and the opening is at least partly closed.
In the gas bag module according to the invention a closure part is provided preferably in the region of the transition from the front wall to the indentation (i.e. the opening), or in the region of the indentation and as close as possible to the front wall, which closure part is actuated by the traction means and at least largely closes the opening or the indentation. The closing force is generated by the gas bag itself during the process of deployment. The opening in the front wall or the indentation thus has a much smaller open cross-sectional area than in the case of a gas bag formed without closure part and without traction means, but otherwise is formed identically.
Preferably, the traction means is on the one hand connected to the gas bag wall and on the other hand to the closure part. The gas bag wall is displaced during deployment, so that the traction means is moved relative to the gas bag wall, whereby the tensile force required for actuating the closure part is produced.
In the completely inflated condition of the gas bag, the traction means preferably runs obliquely outwards, i.e. sidewards, to a lateral portion of the gas bag wall to which it is attached. This formation ensures that the traction means does not produce any recess or indentation in the region of the opening, when the traction means would act as a limiting strap.
The traction means may be arranged outside the gas bag, so as to extend along the gas bag wall, or in accordance with the preferred embodiment in the interior of the gas bag, i.e. within the chamber to be inflated, whereby a relatively plain outside wall is available for the occupant for restraint purposes.
The closure part preferably is a strap or rope surrounding the indentation or the opening.
Furthermore, a guideway is preferably provided in the gas bag wall, in which guideway the closure part is accommodated so as to be movable with respect to the gas bag wall, similar to a bag the opening edge of which has been folded over and sewn, so that the bag can be pulled tight by means of a rope accommodated therein.
Preferably, closure part and traction means are made in one piece, preferably as a strap or a rope.